Cone beam computed tomography evaluation of regenerated buccal bone 5 years after simultaneous implant placement and guided bone regeneration procedures--a randomized, controlled clinical trial

PURPOSE: The aim of this controlled clinical study was to compare a polyethylene glycol membrane (PEG) used for bone regeneration of peri-implant defects to a collagen membrane with respect to implant survival rate, dimensions of buccal peri-implant bone and mucosa. MATERIALS AND METHODS: Thirty-seven patients who received single tooth implants with simultaneous guided bone regeneration (GBR) in the posterior maxilla or mandible were enrolled in the study. Intra-operative heights of bone defects were assessed prior to bone augmentation. The defects were augmented with xenogenic bone mineral and randomly covered either with a porcine collagen membrane (control) or with a PEG membrane (test). Five years after implant placement, clinical evaluation and cone beam computed tomography (CBCT) scans were performed. Remaining height of bone defect, horizontal bone thickness, level of mucosal margin, and mucosal thickness were assessed in CBCT images. The difference of height of bone defect at implant placement and at 5-year follow-up was calculated. The differences between the two groups were analyzed using two-sided t-test and Mann-Whitney U-test. RESULTS: After 5 years, 32 patients could be included and exhibited an implant survival rate of 100% for both groups. The buccal vertical bone gain between implant placement and 5-year follow-up amounted at 4.3 ± 1.5 (SD) mm and 4.8 ± 2.6 (SD) mm for the control and the test group, respectively (P = 0.493). Neither the bone height nor the thickness reached statistical significant differences between the two groups. The distance between mucosal margin and implant shoulder resulted in 0.8 ± 0.7 (SD) mm in the control and 0.5 ± 0.8 (SD) mm in the test group (P = 0.198). The mucosal thickness reached 1.4 ± 0.5 (SD) mm in the control and 1.3 ± 0.3 (SD) mm in the test group (P = 0.715). There were no significant correlations between height of bone defect at baseline and at follow-up examination and between different 5-year parameters. CONCLUSION: A polyethylene glycol membrane used for bone regeneration of peri-implant defects performed as successfully as a collagen membrane with respect to implant survival rate and dimensions of the buccal peri-implant bone and mucosa after 5 years.